Tethered Indenyl−Phosphine Complexes of Ruthenium(II) via Reductive Elimination of a Ruthenium(IV) Complex

The Ru(IV) phosphine complex [(η3,η3-C10H16)RuCl2(κ1P-LH)] (2) was synthesized from the reaction
of [(η3,η3-C10H16)RuCl2]2 with [(C9H7)(CH2)2PPh2] (LH). Treatment of 2 with acid led to halide labilization
to give [(η3,η3-C10H16)RuCl(CH3CN)(κ1P-LH)]+ [2a]+. Reductive elimination of the bis(allyl) ligand in
2 was effected in the reaction of 2, a two- or four-electron ligand (DD), Na2CO3, and KPF6 in EtOH,
resulting in the isolation of PF6 salts of monocationic tethered indenyl Ru species, [(η5,κ1P-L)Ru(DD)]
(3, DD = 1,5-cyclooctadiene (COD); 6, DD = 2,2‘-bipyridyl (bpy)), and neutral tethered indenyl Ru
complexes (4, DD = (PPh3)Cl; 5, DD = (PPh3)H). In addition to [6]PF6, [(κ1P-LH)Ru(bpy)2Cl]PF6,
[7]PF6, was an additional product in the bpy reaction, as was {[(κ1P-LH)Ru(bpy)Cl]2(μ-Cl)3}PF6, [8]PF6, when Na2CO3 was replaced by Li2CO3. In the presence of HCl, [6]+ was found to convert to [8]+,
while [8]+ was converted to [7]+ with bpy and KPF6. The reaction of 2 with acetylacetone (acacH) gave
a high yield of an unusual complex, [(η2,κ1P-LH)Ru(acac)2] (9), in which LH adopts a rare η2,κ1P-coordination mode. The new compounds were all spectroscopically characterized, with 2, 2a, 3, 4, and
9 also determined by single-crystal X-ray diffraction analyses.